Capacitor structures using high-dielectric materials such as (Ba,Sr)TiO.sub.3 (BST) require noble metal electrodes, such as platinum, which are very difficult to pattern using conventional semiconductor processing such as reactive ion etching (RIE), ion beam etching, or chemical-mechanical polishing (CMP). Therefore there is a need for a capacitor structure which does not require a separate patterning step to define the electrodes.
Furthermore, the use of high dielectric constant materials enables a reduction in capacitor area while maintaining the desired charge storage density. In order to minimize cell area, the unusable space (i.e. the separation between adjacent capacitors) should be kept as small as possible.
For purposes of this invention, the term "oxide" layer is used generally to refer to a layer of silicon dioxide, and the silicon dioxide may be undoped or doped, for example, with boron, phosphorous, or both, to form for example borophosphosilicate glass (BPSG), and phosphosilicate glass (PSG). The silicon dioxide layers may be grown or deposited by conventional techniques.